Search

Premium Membership ♕

Limited Time Offer: Save 10% on Pro Plan with coupon: 110VDC. Study specialized LV/MV/HV technical articles & studies.

Home / Technical Articles / Schematics and docs needed for communication systems of substation protective relaying system

Communication circuits

Communication systems of electric utilities have become increasingly critical to electric system protection, operation, and maintenance. For fast tripping and clearing of system faults, communication-aided relaying has become a common protection scheme, particularly in line protection.

Schematics and docs needed for communication systems of substation protective relaying system
Schematics and docs needed for communication systems of substation protective relaying system

Control centers depend on reliable communication channels to remotely operate substation circuit breakers and switches, telemeter electrical quantities of the electric system, and monitor substation alarms.

Maintenance engineering has also become increasingly dependent on communications for remote access to intelligent electronic devices such as relays, remote terminal units, digital fault recorders, and revenue meters.

Because of the increasing dependency on communication systems, electric utilities manage their communication assets through proper documentation with drawings and databases. Documentation of a substation has to address the internal and external communication circuits and the nature of the data that is being communicated.

The area of communication can be split into three areas:

  1. Internal communications: the communication system design internal to the substation that feeds into the external communications and documents relay-to-relay communications;
  2. SCADA: details of the documentation unique to SCADA data; and
  3. External communications: inter-substation communications and the details of the communication media used.

Note that these three areas of communication are all integrated with each other, and there is overlap between these areas.

Table of Contents:

  1. Internal Communications
  2. SCADA Documentation
  3. External Communications:
    1. Communication System Map
    2. Communication System Layout Diagram
    3. Microwave Radio and Fiber Optic Communication Systems Diagram
    4. Communication Channel Circuit Diagram
    5. Database Documentation

1. Internal Communications

IEEE Std C37.1 discusses the importance of block diagrams, addressing the communication block diagram in more detail. The communication block diagram provides a similar function for the communication system as the substation one line provides for the electrical design.

Before any communication design begins, all of the internal and external connections to IEDs should be put on a drawing.

These circuits include:

  1. Remote SCADA communications to one or more entities and/or utilities for operational data
  2. Remote communications to one or more entities and/or utilities for nonoperational data
  3. Inter-substation protective relay communications via various transport methodologies:
    1. Dedicated fiber using proprietary communications
    2. Serial multiplexed signals to a SONET ring
    3. Power line carrier (PLC)
    4. Ethernet
    5. Leased telco circuits
    6. Radio/microwave circuits
  4. Local telco circuits for substation phone and/or data circuits
  5. Revenue metering data circuits

Entities involved for each of these circuits can be one or more utilities, power plants, and independent system operator.

IED Connections

The communication block diagram should detail the following connections for each IED:

  1. Device designation
  2. Device part number (optional)
  3. RS-232 serial communication ports with connector type (terminal block, DB9 male/female) and port number with front or rear indicated as necessary
  4. RS-485 serial communication ports with connector type (terminal block, DB9 male/female) and port number or terminal block number with front or rear indicated as necessary
  5. Ethernet ports with connector type and speed (RJ45: 10/100BaseTX, 10/100/1000BaseTX; ST, MTRJ, LC: 10BaseFX, 100BaseFX) and port number with front or rear indicated
  6. IRIG-B port with connector type (coax, terminal block) and modulation, with a port number or terminal block number with front or rear, indicated as necessary

Device designations can use device number 16 when appropriate. C37.2 added device number 16 to refer to data communications devices and lists suffixes to identify the functions. The first suffix indicates whether the device is serial (S) or Ethernet (E). Subsequent suffixes indicate the following functions: security processing (C), firewall (F), network managed (M), router (R), switch (S), and telephonic (T).

Device designations on the block diagram should match those assigned on nameplates and drawings to provide consistency across the design documentation.

The communication block diagram should connect communications ports together, with cable types indicated by line type and/or line annotation. The organization of the communication block diagram is very important, as the diagram can quickly become a mess of lines that is difficult to read and understand.

Care should be taken when splitting apart the drawing into different drawings for time signal distribution, Ethernet, and serial connections, as this duplicates some similar information shown on various drawings and can be prone to error. The diagram should mimic system architecture and the physical installation if possible, so devices located in adjacent panels are shown adjacent on the drawing.

Figures 1, 2, and 3 are examples of block diagrams. Figure 1 shows a small, simple block diagram for a metering system connected to a generation plant with IRIG-B
connections and network connections are shown.

Figure 1 – Example Block Diagram #1 (click to zoom)

Example Block Diagram #1
Figure 1 – Example Block Diagram #1 (a small, simple block diagram for a metering system connected to a generation plant with IRIG-B connections and network connections)

Figure 2 shows a detail from a larger, more complex conceptual block diagram for a complete substation automation system without the IRIG-B distribution shown. This drawing was completed at the conceptual design stage, well before any detailed design was started. Some protective relay communications are shown.

Note the use of device number 16. For example, 16ERFCM indicates an Ethernet router, managed, with a firewall and VPN for cyber-secure communications.

Figure 2 – Detail from Example Block Diagram #2 (click to zoom)

Detail from Example Block Diagram #2
Figure 2 – Detail from Example Block Diagram #2 (detail from a larger, more complex conceptual block diagram for a complete substation automation system without the IRIG-B distribution)

Figure 3 is a detail from an even larger, more complex block diagram for part of a substation automation system that shows IRIG-B distribution. At the point of the design process, Figure 3 had not yet captured the protective relay communication requirements.

Figure 3 – Detail from Example Block Diagram #3 (click to zoom)

Detail from Example Block Diagram #3
Figure 3 – Detail from Example Block Diagram #3 (part of a substation automation system that shows IRIG-B distribution)

Go back to the Contents Table ↑


2. SCADA Documentation

SCADA is an important part of substation control and protection and its integration to protective relay schematic is very common. The SCADA equipment discussed in this
section is referred to as Substation Remote Terminal Unit (RTU).

This section does not cover the SCADA – Energy Management System that is the SCADA master at utility control/operation center.

Membership Upgrade Required

This content is not available in your premium membership plan. Please upgrade your plan in order to access this content. You can choose an annually based Basic, Pro, or Enterprise membership plan. Subscribe and enjoy studying specialized technical articles, online video courses, electrical engineering guides, and papers.

With EEP’s premium membership, you get additional essence that enhances your knowledge and experience in low- medium- and high-voltage engineering fields.

Limited Time Gift! – Save 10% on Pro Membership Plan with code 110VDC

Upgrade

Already a member? Log in here

Premium Membership

Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! It helps you to shape up your technical skills in your everyday life as an electrical engineer.
More Information
Edvard Csanyi - Author at EEP-Electrical Engineering Portal

Edvard Csanyi

Hi, I'm an electrical engineer, programmer and founder of EEP - Electrical Engineering Portal. I worked twelve years at Schneider Electric in the position of technical support for low- and medium-voltage projects and the design of busbar trunking systems.

I'm highly specialized in the design of LV/MV switchgear and low-voltage, high-power busbar trunking (<6300A) in substations, commercial buildings and industry facilities. I'm also a professional in AutoCAD programming.

Profile: Edvard Csanyi

Leave a Comment

Tell us what you're thinking. We care about your opinion! Please keep in mind that comments are moderated and rel="nofollow" is in use. So, please do not use a spammy keyword or a domain as your name, or it will be deleted. Let's have a professional and meaningful conversation instead. Thanks for dropping by!

1  +  2  =  

Learn How to Design Power Systems

Learn to design LV/MV/HV power systems through professional video courses. Lifetime access. Enjoy learning!

EEP Hand-Crafted Video Courses

Check more than a hundred hand-crafted video courses and learn from experienced engineers. Lifetime access included.
Experience matters. Premium membership gives you an opportunity to study specialized technical articles, online video courses, electrical engineering guides, and papers written by experienced electrical engineers.